A typical solar cell module has the following structure. That is, a plurality of solar cells are arranged in line and are electrically connected to each other to thereby form a cell unit. Then, a plurality of cell units formed as described above are arranged side by side, and the adjoining solar cells located at respective both ends of the cell units are electrically connected to each other through solder-plated wiring members; thus, the solar cells arranged in a form of a matrix are entirely connected to each other in series. Herein, the solar cells and the wiring members are insulated from and protected from the outside by filling resin (EVA (Ethylene Vinyl Acetate) resin), an end-face sealing member (silicone resin) and the like. In this case, the EVA resin has a thermoplastic property and is in a liquid state. Therefore, when the EVA resin is filled into a mold for a solar cell module and, then, is solidified and molded by application of heat at about 150° C., there arises the following problem. That is, air bubbles are generated in the EVA resin and the EVA resin is partly separated from a wiring member and the like, resulting in insulation failure.
Conventionally, a solar cell module is mainly used in an industrial facility. On the other hand, in recent years, a solar cell module tends to be used in a common residence. Therefore, an aesthetic sense of a solar cell module for use in a common residence becomes important. Herein, there arises a problem that a solder-plated wiring material having a silver-color surface is externally conspicuous on a solar cell module formed by a solar cell which is entirely dark in color.
In order to solve these problems, Japanese Patent Laying-Open No. 2003-86820 proposes a structure that a wiring member is partly coated with an insulative coating member in order to achieve a solar cell module with improved insulation performance and improved aesthetic sense.
Hereinafter, brief description will be given of a structure of a solar cell module disclosed in Japanese Patent Laying-Open No. 2003-86820. A solar cell module 1 illustrated in FIG. 58 has the following structure. That is, as illustrated in FIG. 56, a plurality of solar cells 11 (nine in this example) are arranged in line and are electrically connected to each other through wiring members 12 to thereby form a cell unit 13. Then, a plurality of cell units 13 (six in this example) formed as described above are arranged side by side, and the adjoining solar cells (e.g., 11a1 and 11a2, 11b1 and 11b2, 11c1 and 11c2, 11d1 and 11d2, 11e1 and 11e2) located at respective both ends of the cell units are electrically connected to each other through wiring members 41, 42, 43, 44 and 45; thus, a group of solar cells arranged in a form of a matrix (hereinafter, simply referred to as “matrix”) 15 are entirely connected to each other in series.
Then, as illustrated in FIG. 58, sheet-shaped filling resin (such as EVA) 16 and a back cover (back film) 17 are laminated on a bottom face of matrix 15 in which electrical connection is achieved. Further, sheet-shaped filling resin (such as EVA) 18 and a front cover (glass) 19 are laminated on a top face (light receiving face) of matrix 15. A frame member 20 (not illustrated) made of aluminum surrounds outer peripheral edges of these components. Back cover 17, front cover 19, filling resin 16 and 18, and frame member 20 ensure strength performance, moisture-resistant performance and insulation performance.
In FIG. 57, (a) is a sectional view taken along a line A-A in (b) of FIG. 56, and partly illustrates cell unit 13 when being seen sideway. Each connecting member 12 includes a bent stage portion 12a, corresponding to a thickness of solar cell 11, formed at an almost center thereof. Through bent stage portion 12a, one connecting piece 12b is connected with a top face (negative electrode) 11a of solar cell 11 and the other connecting piece 12c is connected with a bottom face (positive electrode) 11b of adjoining solar cell 11. As illustrated in (b) of FIG. 57, connecting member 12 is a rectangular-shaped flat copper wire having a solder-plated surface.
FIGS. 49, 50, 51, 52 and 53 are perspective views respectively illustrating wiring members 41, 42, 43, 44 and 45 each of which is obtained as follows: a rectangular-shaped flat copper wire having a solder-plated surface is partly coated with an insulative coating member. Herein, the adjoining solar cells (e.g., 11a1 and 11a2, 11b1 and 11b2, 11c1 and 11c2, 11d1 and 11d2, 11e1 and 11e2) are connectable to each other. More specifically, the wiring member is formed into an almost “L” shape or an almost “F” shape in accordance with a part where the adjoining solar cells are connected to each other. In accordance with a shape of the connection part, a shape of the wiring member is determined. In the example disclosed in Japanese Patent Laying-Open No. 2003-86820, there are required seven wiring members of five types in accordance with an arrangement method of solar cells 11, orientation of an electrode, a position of an electrical output extracting port, and the like.
As illustrated in FIG. 49, for example, wiring member 41 includes a coupling piece 41a having a width of 6 mm and a thickness of 0.23 mm, and two protruding pieces 41b and 41b each having a width of 1.5 mm and a thickness of 0.15 mm. Protruding piece 41b connects coupling piece 41a to an electrode on a bottom face of each of solar cells 11a2, 11c2 and 11e2 (see FIG. 44). Wiring member 41 is formed into an almost “F” shape as a whole by connection by soldering between coupling piece 41a and protruding pieces 41b and 41b or by punching. Coupling piece 41a is entirely coated with an insulative coating member 411 (diagonally shaded). However, in coupling piece 41a, an end 41a1 located opposite to protruding pieces 41b and 41b and a portion 41a2 close to a center relative to end 41a1 are spaced away from each other by a predetermined distance, and coating member 411 is removed therefrom. Bare portions 41a1 and 41a2 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to each of solar cells 11a1, 11c1 and 11e1 (see FIG. 44). As is clear from FIGS. 50 to 53, each of other wiring members 41, 42, 43, 44 and 45 is also formed into a predetermined shape by a combination of a coupling piece and protruding pieces, and predetermined portions are coated with a coating member.
FIG. 54 illustrates examples of sectional structures of coated portions of wiring members 41, 42, 43, 44 and 45. In the drawing, dimensions of the respective components are described as one example. More specifically, a solder-plated copper wire having a width of 6 mm and a thickness of 0.23 mm, a solder-plated copper wire having a width of 1.5 mm and a thickness of 0.15 mm, and the like are formed by soldering into an almost “F” shape, an almost “E” shape, an almost “L” shape or the like; thus, integrated copper-wire formed bodies 41a to 45a are formed. Then, copper-wire formed bodies 41a to 45a are coated with films 411 to 451 such as a PET film, respectively. Films 411 to 451 are excellent in insulating performance and have various colors. This coating operation uses an adhesive, a double-faced tape or the like.
As the coating method, as illustrated in FIG. 54, generally, one of insulating films 411 to 451 is folded in two and the copper-wire formed body is sandwiched therebetween. According to this method, a deviation of a copper-wire formed body is suppressed upon adhesion, and insulation performance is ensured. Herein, the copper-wire formed body is covered with EVA resin upon manufacturing of a solar cell module in a subsequent step. Therefore, completed wiring members 41, 42, 43, 44 and 45 must be previously subjected to vacuum lamination or deaeration in order to prevent generation of air bubbles in the EVA resin. In addition, an adhesive or a double-faced tape which does not exert an adverse influence on the EVA resin must be selected herein. Further, since wiring members 41, 42, 43, 44 and 45 are mainly connected by soldering, it is preferable that coating members 411 to 451 are excellent in heat-resistant property.
As illustrated in FIG. 55, each of a tip end of coating member 441 for coating protruding piece 44c of wiring member 44 in FIG. 52 and a tip end of coating member 451 for coating protruding piece 45c of wiring member 45 in FIG. 53 has a tapered face P cut obliquely. Tapered face P exhibits the following advantage. That is, when bare portion 44c1 of wiring member 44 and bare portion 45c1 of wiring member 45 are derived from electrical output extracting ports 25a and 25b formed in back cover 17 made of a conductive film to the outside, the tip ends (tapered faces P) of coating members 441 and 451 can smoothly pass through electrical output extracting ports 25a and 25b without catch in peripheral portions of electrical output extracting ports 25a and 25b. 
Next, description will be given of a wiring step using wiring members 41, 42, 43, 44 and 45 each configured as described above, with reference to FIGS. 44 to 48. First, as illustrated in FIG. 45, three first wiring members 41, 41 and 41 are arranged along the adjoining solar cells (e.g., 11a1 and 11a2, 11c1 and 11c2, 11e1 and 11e2) located at a side edge of matrix 15. In this state, bare portions 41a1 and 41a2 of uppermost wiring member 41 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to solar cell 11a1 with the use of a soldering iron or the like. Then, protruding pieces 41b and 41b of wiring member 41 are connected by soldering to an electrode on a bottom face of solar cell 11a2 with the use of a soldering iron or the like.
Similarly, bare portions 41a1 and 41a2 of middle wiring member 41 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to solar cell 11c1 with the use of a soldering iron or the like. Then, protruding pieces 41b and 41b of wiring member 41 are connected by soldering to an electrode on a bottom face of solar cell 11c2 with the use of a soldering iron or the like.
Similarly, bare portions 41a1 and 41a2 of lowermost wiring member 41 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to solar cell 11e1 with the use of a soldering iron or the like. Then, protruding pieces 41b and 41b of wiring member 41 are connected by soldering to an electrode on a bottom face of solar cell 11e2 with the use of a soldering iron or the like. In FIG. 45, circular marks indicate soldered connection portions.
Next, wiring member 42 is arranged along the adjoining solar cells (11b1 and 11b2) located at an upper center of an edge of matrix 15 (see FIG. 45). In this state, bare portions 42a1 and 42a2 of wiring member 42 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to solar cell 11b1 with the use of a soldering iron or the like. Then, protruding pieces 42b and 42b of wiring member 42 are connected by soldering to an electrode on a bottom face of solar cell 11b2 with the use of a soldering iron or the like.
Next, wiring member 43 is arranged along the adjoining solar cells (11d1 and 11d2) located at a lower center of the edge of matrix 15 (see FIG. 45). In this state, bare portions 43a1 and 43a2 of wiring member 43 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to solar cell 11d1 with the use of a soldering iron or the like. Then, protruding pieces 43b and 43b of wiring member 43 are connected by soldering to an electrode on a bottom face of solar cell 11d2 with the use of a soldering iron or the like.
Thereafter, a bypass diode (not illustrated) is connected between a tip end 42c1 of protruding piece 42c of wiring member 42 and a tip end 43c1 of protruding piece 43c of wiring member 43.
Next, wiring member 44 is arranged so as to extend from the center of the side edge to an upper end in matrix 15 (see FIG. 46). In this state, protruding pieces 44b and 44b of wiring member 44 are connected by soldering to an electrode on a bottom face of solar cell 11f with the use of a soldering iron or the like. Then, tip end 44c1 of protruding piece 44c of wiring member 44 is derived from electrical output extracting port 25a to the outside.
Next, wiring member 45 is arranged so as to extend from the center of the side edge to a lower end in matrix 15 (see FIG. 46). In this state, bare portions 45a1 and 45a2 of wiring member 45 are connected by soldering to the other connecting pieces 12c and 12c of connecting members 12 attached to solar cell 11g with the use of a soldering iron or the like. Then, a tip end 45c1 of protruding piece 45c of wiring member 45 is derived from electrical output extracting port 25b to the outside.
In addition, a bypass diode (not illustrated) is connected between tip end 42c1 of protruding piece 42c of wiring member 42 and tip end 44c1 of protruding piece 44c of wiring member 44.
Moreover, a bypass diode (not illustrated) is connected between tip end 43c1 of protruding piece 43c of wiring member 43 and tip end 45c1 of protruding piece 45c of wiring member 45.
FIGS. 46 and 47 respectively illustrate a state after completion of the aforementioned wiring step. The other connecting pieces 12c, 12c, . . . protruding from the side edge of matrix 15 are cut after completion of the wiring step (shown by broken lines in FIG. 46). FIG. 48 is a partly enlarged view illustrating a positional relation between wiring members near electrical output extracting ports 25a and 25b. In FIG. 45, circular marks indicate soldered connection portions. The number of soldered connection portions of wiring members 41, 42, 43, 44 and 45 formed as disclosed in Japanese Patent Laying-Open No. 2003-86820 is 24.
However, in the structure of the typical solar cell module, wiring member 43 (45) for electrically connecting between the adjoining solar cells located at the both ends of the cell units intersects with wiring member 42 (44) for extracting an electrical output; therefore, a step of connecting a wiring member for connecting between adjoining solar cells and a step of connecting a wiring member for extracting an electrical output are implemented independently. Consequently, positional deviations of wiring members 42 and 44 or wiring members 44 and 45 are occurred, so that insulation performance failure due to a variation in outer appearance and a deviation in distance to a module end is occurred.
It is indispensable for a cell unit to perform positional adjustment for respective wiring members. Therefore, a frequency of positional adjustment work must be increased in accordance with the number of wiring members in addition to the connection by soldering between the wiring member and the cell unit. In view of the ensuring of an insulation distance between wiring members 44 and 45 for extracting an electrical output and the end of the cell unit or an insulation distance between wiring members 44 and 45 and an outer periphery of a module, such as a frame member made of aluminum, as the frequency of the positional adjustment work is increased, a margin due to a positional deviation must be secured excessively and an area of a module region which does not contribute to power generation is increased, so that power generation efficiency per unit area as a solar cell module is lowered.
Since wiring members 44 and 45 for extracting an electrical output are connected and fixed only by solar cells 11f and 11g located at the matrix end, the wiring members are flexed when being led out to the center of the solar cell module. Consequently, it is difficult to perform positional adjustment and to control arrangement of wiring members when the EVA resin filled into a mold is thermally solidified, so that a variation in outer appearance is occurred.
In order to decrease the number of wiring members, it is considered that wiring members 42 and 44 or wiring members 43 and 45 are simply integrated with each other. However, a coating member which has a color identical to that of back cover 17 and ensures a heat-resistant property is rare and expensive. Consequently, such a coating member is not practically used. That is, coating member 441, which is insufficient in heat-resistant property when connecting pieces 12c are connected by soldering to bare portions 42a1 and 42a2, is broken due to heat generated in the connection by soldering, resulting in insulation failure.
If connecting pieces 12c are connected by soldering to bare portions 42a1 and 42a2 from the back side of wiring member 44 in a state where wiring member 42 is integrally overlaid on the back side of the wiring member 44, protruding piece 44b must be arranged on the back face of solar cell 11f, connecting pieces 12c must be led out from the top face of solar cell 11b1 and must be arranged in bare portions 42a1 and 42a2, and protruding piece 44b must be arranged on the bottom face of solar cell 11b2. That is, it is necessary that a wiring member obtained by integrating wiring members 42 and 44 with each other is arranged so as to weave the front and back sides of adjoining cell units alternately, resulting in complicated work.
It is considered herein that a current twice in amount is to be obtained by cell units connected in parallel. In order to eliminate loss as much as possible when string arrangements are arranged in serial, in the conventional arrangement where adjoining cell units are arranged upside down (polarities of adjoining cells in a direction almost orthogonal to a connecting direction of cell units are changed alternately, like positive, negative, positive, negative, . . . ), the wiring member must be arranged so as to weave the front and back sides of adjoining cell units alternately, resulting in complicated work.
Accordingly, as in the conventional technique, wiring members 42 and 44 or wiring members 43 and 45 must be arranged in a division manner so as to suppress complication.
Patent Document 1: Japanese Patent Laying-Open No. 2003-86820